arXiv subjects

Jiri Vacik

Publications and source records attributed to Jiri Vacik.

5 recordsLinked to original sources

arXiv2026

Morphological Evolution of Nickel-Fullerene Thin Film Mixtures

Hybrid systems consisting of metal-fullerene composites exhibit intriguing properties but often suffer from thermal instability. With proper control, such instability can be harnessed to enable the formation of sophisticated nanostructures with nanometric precision. These self-organization phenomena are not limited to thermal stimulation alone but can also be triggered by other external stimuli. In this work, we investigate the morphological evolution of thin films composed of evaporated C60 and sputtered nickel mixtures, focusing on how external stimuli influence both their structural and electrical properties. Thin films were prepared under controlled deposition conditions, and their surface morphology was analyzed using advanced characterization techniques. Progressive changes in film morphology were observed as a function of composition and external treatment, highlighting the interplay between metallic and molecular components. In particular, it was observed that, due to the annealing treatment, the sample undergoes strong phase separation, with the formation of structures tens of microns in diameter and an increase in electrical resistance, exhibiting insulating behavior. These findings provide insights into the mechanisms governing hybrid thin film formation and suggest potential applications in electronic, optoelectronic, and energy-related devices.

cond-mat.mtrl-sci↗

arXiv2026

Effects of pulsed and continuous light and heavy ion irradiation on the morphology and electrical properties of Ag+C60 and Au+C60 composite thin films

Metal - organic nanocomposite thin films represent a versatile class of materials whose properties can be effectively tuned through external stimuli. In this study, Ag+C60 and Au+C60 nanocomposite thin films were briefly investigated to elucidate the effects of ion irradiation on both their morphology and electrical properties. The films were synthesized by co-deposition of noble metals and fullerenes, using ion beam sputtering of metal targets combined with simultaneous thermal evaporation of C60. The as - deposited films were characterized by ion beam analysis to determine their composition and element depth distributions. Subsequently, the samples were irradiated at room temperature with either a continuous Ar ion beam or a pulsed C ion beam, both at an energy of 20 keV and a fluence of 1 x 1015 ions/cm2. Irradiation-induced morphological changes were examined by scanning electron microscopy. While the C-irradiated films retained compact and homogeneous surface morphologies, Ar irradiation induced pronounced surface restructuring, resulting in highly corrugated and porous-like surfaces. In addition to morphology, the electrical resistance of the films was measured. The results indicate that C-irradiated samples exhibit only minor changes in resistivity, whereas Ar irradiation strongly affects the electrical properties, with the most significant impact observed for the Au+C60 system. The observed changes in electrical resistance closely correlate with the irradiation-induced surface morphology. The measurement results are briefly discussed below.

cond-mat.mtrl-sci↗

arXiv2026

NASICON solid-electrolyte modification and analysis using ion and neutron beams

Solid electrolytes (SEs) for sodium-based superionic conductors (NaSICON) are widely recognized for their excellent ionic conductivity and application in sodium based energy storage systems. While considerable effort has been made to develop thin electrolytes for all-solid-state batteries (ASSBs) for lithium ions, only a few sodium-based SEs have been successfully fabricated as thin films. These thin films are particularly desirable for their reduced electrical resistance, which typically increases with the thickness of the SE. By reducing the thickness of the SEs to the nanometer scale, their ionic conductivity can be significantly enhanced. In this study, the NASICON composite was initially prepared in the form of pellets using the mixed oxide technique with a planetary ball mill and synthesized by the solid-state method at 1250 {\deg}C. The resulting pellets were used as sputtering targets in a low-energy ion facility to prepare continuous and uniform NASICON nanofilms. To explore the effect of ion implantation on the electrical properties of NASICON, the prepared films were bombarded with Ni ions at 1.1 MeV and varying fluences, using the Tandetron accelerator at the CANAM infrastructure (NPI \v{R}e\v{z}). The electrical properties of both the synthesized and implanted films were analyzed through electrochemical impedance spectroscopy (EIS). The results, describing the impact of irradiation on NASICON's properties, are presented here.

cond-mat.mtrl-sci↗

arXiv2025

Measuring the buried interphase between solid electrolytes and lithium metal using neutrons

Interfaces are the key to next generation high energy batteries including solid state Li metal batteries. In solid state batteries, the buried nature of solid solid electrolyte electrode interfaces makes studying them difficult. Neutrons have significant potential to non destructively probe these buried solid solid interfaces. This work presents a comparative study using both neutron depth profiling (NDP) and neutron reflectometry (NR) to study a model lithium metal-lithium phosphorus oxynitride (LiPON) solid electrolyte system. In the NDP data, no distinct interphase is observed at the interface. NR shows a difference between electrodeposited, and vapor deposited LiPON -Li interfaces but finds both are gradient interphases that are less than 30 nm thick. Additional simulations of the LiPON-Li2O-Li system demonstrate that NDP has an excellent resolution in the 50 nm-1 mm regime while NR has an ideal resolution from 0.1 - 200 nm with different sample requirements. Together NDP and NR can provide a complementary understanding of interfaces between Li metal and solid electrolytes across relevant length scales.

cond-mat.mtrl-sci↗

arXiv2012

Luminescence of Nanodiamond Driven by Atomic Functionalization: Towards Novel Biomolecular Detection Principles

High biocompatibility, variable size ranging from ~ 5 nm, stable luminescence from its color centers and simple carbon chemistry for biomolecule grafting make nanodiamond (ND) particles an attractive alternative to molecular dyes for drug-delivery. Here we present a novel method for remote monitoring of chemical processes in biological environment based on color changes from photo-luminescent NV centers in ND. We propose to drive the NV luminescence chemically, by alternating the surface electric field developed by interacting atoms and molecules with the diamond surface. Due to the small ND size, the developed electric field penetrates into the bulk of the nanoparticle and intermingles with the electronic NV states. This allows construction of optical chemo-biosensors operating in cells, visible in classical confocal microscopes. We demonstrate this phenomenon on oxidized and hydrogenated ND as well as single crystal diamond containing engineered NV centers. Hydrogenation of NDs leads to quenching of luminescence related to negatively charged (NV-) centers and by this way produces color shifts from NV- (636 nm) to neutral NV0 (575nm) luminescence. We model how the reduction of diamond size increases the magnitude of NV color shift phenomena.

cond-mat.mtrl-sci↗